Fans of probiotic drinks and foods may be wasting their money, according to a review of current research into the supplements that suggests they may be of no benefit to healthy adults.
A Danish team looked at the results of seven trials of the products – often sold as milk-based drinks, biscuits, sachets, or capsules – and found no evidence they changed the composition of faecal bacteria in healthy adults.
Online blogs and magazines have helped spur a trend for lacto-fermentation of foodstuffs by touting a range of purported health benefits, such as improved digestion and resistance to infections.
Oluf Pedersen, who led the research at the University of Copenhagen, said:
“While there is some evidence from previous reviews that probiotic interventions may benefit those with disease-associated imbalances of the gut microbiota, there is little evidence of an effect in healthy individuals.”
OK, so where is the actual review?
You can find it here within Genome Medicine (and there is no paywall so you get the full text).
Now for a couple of additional notes on it.
Note 1 : This is not a new study and was just a review of existing studies
They conducted a search of PubMed, SCOPUS, and ISI Web of Science looking for peer-reviewed studies and identified seven RCTs (randomized controlled trials) that specifically tested the impact of probiotic supplementation on the fecal microbiota for healthy adults.
- The raw count from the search yielded 1368 hits, and that then dropped to 1287 once duplicates were eliminated.
- After screening what they had, they then only had 31 left
- That was then whittled down to 7 by eliminating RCTs that did not tick all their boxes (for example if a study also included unhealthy individuals, it was excluded)
Note 2 : The results
The seven studies were determined to be of medium to high quality, and generally they found that they all recorded that …
no effects were observed on the fecal microbiota composition in terms of α-diversity, richness, or evenness in any of the included studies when compared to placebo
except …
one study found that probiotic supplementation significantly modified the overall structure of the fecal bacterial community in terms of β-diversity when compared to placebo.
…however, some of the studies where not without problems, for example three did not conduct proper blinding, and two had a specific potential for bias.
Note 3 : The conclusions
Their review states …
Overall, this systematic review demonstrates that there is no convincing evidence for consistent effects of probiotics on fecal microbiota composition in healthy adults.
No effects were observed on the fecal microbiota composition in terms of α-diversity, richness, or evenness in any of the included studies when compared to placebo
I should however add that they do note that if your microbiota (if I may borrow their term) is “perturbed”, then …
there is some evidence for a restorative or protective effect of certain strains of probiotics, both on the fecal microbial community itself, but more importantly, also on host physiology, e.g. alleviation of gastrointestinal symptoms
Bottom Line
What this review actually does is to pick out the good quality studies, then merges the results statistically. The net effect yields a much stronger and more reliable result than a single isolated study would produce, hence it is important to recognise that reviews like this do bring additional value to the conversation and is not just a rehash of what has already been done.
This combined merged statistical result confirms that if you are a healthy adult and are buying and consuming probiotic products because you want to “improve” the quality of the bacteria within yourself in order to gain even better health, then you are in all probability flushing your hard earned cash down the pan.
The manufacturers of these products previously sold them with claims of health benefits. Now however, buried within some EU body is a vast collection of these rejected claims they have promoted, and I don’t mean just a few, but hundreds.
Why are the EU involved?
This is because a health claim for a food can only be made if it is listed on the EU Register, and so they have had to submit such claims to the EU for approval, but because these claims are unverified then the EU has clamped down and explained “No, you can’t claim that, there is no evidence for that claim”, and so the claims you would have previously seen not too long ago have vanished. In fact it has been decided that they cannot even brand their products as “probiotics” because that word itself is an unverified claim.
You might perhaps not like the idea of the EU imposing such restrictions, but before you do that, you should pause and remember that this is done to stop manufacturers of food products marketing products to you with health claims that are simply not true, and that is actually quite a good thing for consumer protection.
Spending money on this stuff is either a tax on gullibility or perhaps simply highlights how susceptible we can be to clever but wholly unconfirmed marketing claims.